The animals were sickened with a human gene that caused them to develop, at an accelerated rate, the disease that robs millions of elderly people of their memories. After receiving the doctored cells, the brain-muddling plaques melted away. If this works in humans, old age could be a much happier time of life.

If it works in humans (and that's a big "if"), it would seem we've finally stumbled onto a treatment, if not a cure.